Production of hollow reinforced-concrete slabs.



M. MILANKOVITGH.

PRODUCTION OF HOLLOW REINFORCED GONGRETE SLABSM APPLICATION PILBD'JUNE15, 1909.

940,041; Patented Nov. 16,1909.

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UNITED STATES PATENT OFFICE.

PRODUCTION OF HOLLOW REINFORCED-CONCRETE SLABS.

Specification of Letters Patent.

Patented Nov. 16, 1909.

Application filed. June 15, 1909. Serial No. 502,259.

To all whom it may concern:

Be it known that I, MILUTIN MILANKO- vrrcrr, a subject of the Emperor ofAustria and King of Hungary, and resident of Vienna IV, Austria-Hungary,have invented a certain new and useful Improvement in the Production ofHollow Reinforced-Concrete Slabs, of which the following is aspecification.

This invention has for its object the production by means of patterns ofhollow Ieinforced concrete slabs having flat under sides. The use ofpatterns for the formation of hollow parts in the slabs is already knownbut a rational method has hitherto been wanting which will not onlyallow of an easy casting of the slab but also of the simple removal ofthe patterns for repeated use without causing weakening of the up-- perplate at those parts where it is required as a support for the slab.

The method forming the subject of the present invention overcomes thedifficulty in that the upper plate formed simultaneously with the ribsover the pattern is removed at those places where it is not required asa support for the slab in order to form openings in the otherwisemonolithically produced slabs, which simplifies the removal of thepatterns, these openings being covered later by cast plates. Inconnection therewith the invention also includes the construction of apattern which in consequence of its special mode of construction allowsthis easy removal from the hollow spaces in the slab after setting ofthe concrete.

In the accompanying drawing Figures 1 and 2 show in section a slabproduced according to the invention in two planes at right angles to oneanother and Figs. 3 and 4 show to enlarged scale a transverse sectionand part longitudinal section of the pattern itself.

The method of production is as follows On the base (not shown)constructed in the usual manner is first stamped a plate a forming theflat lower side and on this the patterns are laid the distance betweenwhich determines the thickness of the ribs 6 formed between them. In thelatter are inserted the reinforcements i and supporting ties In. Theupper plate m above the upper side of the pattern is constructedsimultaneously I with the rib b and then bound and allowed to set.

In order to remove the pattern from the slab easily for repeated useaccording to the invention the upper plate m is removed at those placeswhere it is not required as a support, that is near the supportingpoints in which by the casting of a slab over the pattern longitudinalpassages n and also passages 0 are left which simplify the removal ofthe pattern, these being afterward closed by cast plates 79 (Fig. 2). Inorder to simplify removal the patterns are preferably constructed, asshown in Figs. 3 and 4, from three pieces 0, d and f of which the twoparts 0 and d form almost symmetrically shaped angle pieces whichdetermine the size of the ribs and whose meeting edges 6 are beveled.

On its upper edge rests the cover piece f of the pattern which springsback somewhat against the outer faces of the side walls in order toprevent it from uniting with the concrete. The sides are secured to oneanother by withdrawable pins 8 and to the cover by bolts t arranged onit and engaging in corresponding holes in the sides. Moreover, the coverpieces are connected with one another by bolts u and slots '0 and thepatterns are arranged one behind the other in order to prevent lateralmovement of the same.

The removal of the patterns after binding or setting of the ribs andupper plate is effected by withdrawing the pins 8 in order to releasethe two sides which are drawn out by a lateral rotation and are thenbrought under the opening 0 the cover pieces being thereupon released inthe same manner as the side pieces.

Having described my invention what I claim and desire to secure byLetters Patent of the United States is 1. Method of producing hollowreinforced concrete slabs by means of patterns with fiat lower surfaces,consisting in casting the upper plate over the lower platesimultaneously with the ribs between the patterns in removing the upperplate at those points where it is not required as a support, in order toprovide openings for the removal of the pattern, and then covering saidopenings with cast pieces.

2. Means for producing reinforced con- In testimony whereof I havesigned my name to this specification in the presence of 16 tWosubscribing- Witnesses.

MILUTIN MILANKOVITCH.

Witnesses:

VVILHELM BERGER, ROBERT WV. HEINGARTNER.

